Question

In a textfield I should write a number: this number can be with point (10.23) or without poin (10); but I should to check that this number is a number and not a word. Can I check if in a textfield there is a number instead a word?
Example: if I write a word instead a number I want an nslog that say that there is an error.

Answer 1

Another way:

NSString *string = @"684.14";
NSCharacterSet *decimalSet = [NSCharacterSet decimalDigitCharacterSet];
BOOL stringIsValid = ([[string stringByTrimmingCharactersInSet:decimalSet] isEqualToString:@""] || 
                      [[string stringByTrimmingCharactersInSet:decimalSet] isEqualToString:@"."]);

Also remember that you can use textField.keyboardType = UIKeyboardTypeNumberPad; for the keyboard. (This won’t guarantee only numeric entries, however, it’s just about user friendliness.)